In the Next Generation Network (NGN), the Quality of Service (QoS) problem is particularly conspicuous since the bearer network applies the packet technology, thus the International Telecommunication Union (ITU) provides a Resource and Admission Control Function (RACF) to solve the QoS problem in the NGN bearer network. The main function of the RACF is to control the resource and admission based on the operating strategy according to user subscription QoS information and the network internal available resource. The RACF shields the difference of the bearer layer from the application layer, and maps the QoS attribute of the application layer to the bearer layer to make the bearer layer transport entity provide QoS guarantee to the media stream of the session under its guidance.
In the latest RACF draft of ITU, the functional framework of the RACF is as shown in FIG. 1, wherein, the Policy Decision Function Entity (PD-FE) acquires media stream session information from the Service Control Function (SCF) via the Rs interface and acquires the transport resource subscription information from the Network Attachment Control Function (NACF) via the Ru interface to make the preliminary QoS policy, and then interact with the Transport Resource Control Function Entity (TRC-FE) to determine whether there is enough QoS resource or not, and then make the final policy, and then send the policy to the Policy Execute Function Entity (PE-FE) for execution.
The TRC-FE is mainly responsible for resource control, and it monitors the network resource and collects the related information and makes a response when the PD-FE requests for resource according to the specific resource condition.
The PE-FE mainly performs the policy control (gating, bandwidth, traffic sorting and labeling, traffic shaping, layer 2 and layer 3 QoS mapping, and collecting and reporting the resource use information) under the guidance of the PD-FE.
The TRE-FE is currently described in protocol to execute the layer 2 policy related to the transport technology under the guidance of the TRC-FE, however its specific function and scope are not determined yet.
In recent years, the fixed network operators' income from voice and broadband services increases more and more slowly, and based on the change of competition and demands, the fixed network operators need to operate from the single service such as pure data or voice to multi-service as combination of video, voice and data, so as to retain and attract more domestic customers. In view of the technology and products, terminal products capable of supporting a plurality of services and a plurality of ports, and distinguishing different QoSs, that is, the Home Gateway (HG), and the QoS control is the key for the operators developing the digital home service.
FIG. 2 illustrates how the RACF performs policy control for HG currently, and in FIG. 2:
The Home Policy Execute Function Entity (HPE-FE) is a PE-FE located in the HG and it receives the policy issued by the RACF and performs policy control for the user's service traffic according to the policy.
When a user initiates a QoS guaranteed service, the QoS of the service is determined by negotiation of the service layer, and the service control layer sends a resource request to the RACF according to the negotiated QoS, and the RACF generates the QoS policy of the transport layer and sends it to the transport layer policy execute entity (including the HPE-FE in the HG) for execution, and the specific flow is as shown in FIG. 3 and comprises the following steps:
Step 301: the SCF sends a resource request to the PD-FE according to the QoS negotiated by the service layer;
Step 302: the PD-FE authorizes the request and makes the preliminary policy, and if there is no user subscription information in the PD-FE, the PD-FE acquires the user subscription information by interacting with the NACF;
Step 303: the PD-FE requests the TRC-FE for resource, and the TRC-FE makes decision for the request according to the condition of the current resource and returns the information on whether there is enough available resource or not;
Step 304: the PD-FE makes the final admission policy decision according to the resource availability;
Step 305a, b: the PD-FE issues the policy to the HPE-FE and the PE-FE respectively;
Step 306a, b: the HPE-FE and the PE-FE returns an acknowledgement to the PD-FE respectively;
Step 307: the PD-FE returns a resource request acknowledgement to the SCF.
However, the following problem exists in the above method: since there are a lot of HGs and the HGs are scattered at the edge of the network, the RACF function is too complicated if it directly controls the HGs and issues policy to the HGs, which equals integrating partial capability of the network management.